Physical Fitness and Mitochondrial Respiratory Capacity in Horse Skeletal Muscle
Figure 1
Respirometric protocols with permeabilized fibres from horse skeletal muscle (triceps brachii).
A: SUIT1 protocol with electron flow through CI supported by glutamate+malate. B: SUIT2 protocol with electron flow through CI supported by pyruvate+malate. C: SUIT3 protocol with electron flow through CII. Left panels: Oxygen concentration (µM; blue lines) and muscle mass-specific oxygen flux (pmol O2·s−1·mg−1 wet weight; red lines). Marked sections correspond to steady-state fluxes at different coupling states (L, P and E) and substrate states. Numbers on top of traces are ROX-corrected tissue mass-specific fluxes at various metabolic states, and ROX (pmol O2·s−1·mg−1). Right panels: Coupling/substrate control diagrams with flux control ratios (FCR) normalized relative to ETS capacity with convergent CI+II electron input (values framed). Values linked to vertical and horizontal arrows are coupling control ratios (L/P and P/E ratio), and substrate control ratios (CI/CI+II in the OXPHOS state). FCR linked by arrows directly to the reference state are also coupling control ratios (P/E) or substrate control ratios (CII/CI+II). Whereas internal FCR are obtained in SUIT 1 and 2 (A and B), the FCR for SUIT3 (C) are calculated for the externally determined reference state (Ref in C averaged from SUIT1 and 2 protocols).